However, a hurricane hunter aircraft on Monday morning determined the system has yet to develop a closed circulation, and it has not strengthened in the past few hours, the hurricane center said in its 2 p.m. tropical outlook.

The plane found that the system has near tropical force winds and that the atmosphere remains ripe for it to intensify, hurricane specialist Stacy Stewart said. But without the closed circulation, the disturbance for now remains a large area of low pressure and clouds.

Because of dry air and wind shear, hampering the system, the hurricane center lowered the chance of its developing - over the next two days - from 90 percent on Monday morning to 80 percent this afternoon.

Models continue to aim the system toward the Puerto Rico, Hispaniola and the Bahamas. Some models bring the system close to South Florida on Friday.

Still, until a bona fide tropical system spins up, the models won't have a good handle on the tropical wave's most likely path. For now, all that is certain is that it is moving west-northwest at 15-20 mph.

Whether or not the disturbance develops, the northern Windward Islands and the Leeward Islands can expect heavy rain and gusty winds on Monday, the hurricane center said.